There is one huge factor when it comes to playing teams like Forest. Every time we moved the ball near their penalty area, they defended with 9 people behind the ball.
It doesn't really matter what patterns of play you use, what drills you do or how well coached your team is in these situations. These things help as far as bringing the ball in danger area. After that - individual class comes into play.
When there is no space to attack and no obvious pass, it comes to the ability of players to improvise, beat a man, make a trick shot etc.
And this applies to every team ever.
Sure, in an open game the better coached team will win most of the times. But when one team is defending tightly with many bodies, it will always be down to players individual class.
This season in every game we played against defensive teams, we bring the ball to the penalty area again and again and we simply cannot find a solution. This is mostly on the players. In these situations you'll expect your wingers to beat a man, so they can get inside the box. And our wingers are hopeless. Garnacho has the pace to beat a defender when he's on the run. When he has to beat the defender face to face, he fails 95% of the time. Rashford, Antony, Pellistri... All hopeless in 1vs1 situations. Actually Sancho is the one winger who has shown some kind of ability to beat a man on the spot, but he turned out to be a massive, lazy twat.
Usually when the wingers can't get inside, the ball gets passed back to Bruno, who attempts some insanely stupid cross to nobody.
Another big problem - either the players don't expect our wingers to beat the defence and get inside the box, or they are not coached to attack the box. Because when rarely we manage to get a fullback or winger inside, we only have 1 attacker vs 3-4 defenders to attack the ball. And when we attempt to cut back the ball, Bruno and the other midfielders are too far behind and the pass gets intercepted. Also, Hojlund is not quick enough to react to fast crosses. He seems to be 1-2 steps behind and on a few occasions it looks like if he had started his run earlier, he would have scored.
So it's both down to coaching and players class, but against tight defences the latter is what makes a difference. It will always be like this.